There's no such thing as a free phone call

Electronics magazines in Britain are this month carrying what British Telecom reckons must be the cheekiest ever advert for a telephone gadget.

'Slash your phone bills!!! 100% free dialling!!!' promises the advertiser, a company called Top Secret Electronics. 'After months of legal battles we can now offer you the Creditcall from the inventors of the original Black Box.'

The Black Box was developed in the US 20 years ago by electronics buffs, known as 'phone phreaks'. It fooled the telephone system into giving subscribers free calls.

'Simply plug the remarkable Creditcall into any authorised socket, then plug your telephone into the Creditcall. It works by blocking the metering pulses on the line and suppressing the charge signals,' explains the advert. 'Save a fortune! Just £34.95 plus £2.50 postage and packing.'

BT's engineers bought Creditcall and several similar devices now on sale and tested them. All looked like a modified two-way ...

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